package com.indusfo.spc.interceptor;

import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.exceptions.JWTDecodeException;
import com.auth0.jwt.exceptions.JWTVerificationException;
import com.indusfo.spc.annotation.PassToken;
import com.indusfo.spc.annotation.UserLoginToken;
import com.indusfo.spc.pojo.User;
import com.indusfo.spc.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;


/**
 * 拦截器
 * @ 用来判断用户的
 *1. 当preHandle方法返回false时，从当前拦截器往回执行所有拦截器的afterCompletion方法，再退出拦截器链。也就是说，请求不继续往下传了，直接沿着来的链往回跑。
 2.当preHandle方法全为true时，执行下一个拦截器,直到所有拦截器执行完。再运行被拦截的Controller。然后进入拦截器链，运
 行所有拦截器的postHandle方法,完后从最后一个拦截器往回执行所有拦截器的afterCompletion方法.
 */


public class AuthenticationInterceptor implements HandlerInterceptor
{

  @Autowired
  private UserService userService;

  @Override
  public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object object) throws Exception {
    String token = httpServletRequest.getHeader("token");// 从 http 请求头中取出 token
    // 如果不是映射到方法直接通过
    if(!(object instanceof HandlerMethod)){
      return true;
    }
    HandlerMethod handlerMethod=(HandlerMethod)object;
    Method method=handlerMethod.getMethod();
    //检查是否有passtoken注释，有则跳过认证
    if (method.isAnnotationPresent(PassToken.class)) {
      PassToken passToken = method.getAnnotation(PassToken.class);
      if (passToken.required()) {
        return true;
      }
    }
    //检查有没有需要用户权限的注解
    if (method.isAnnotationPresent(UserLoginToken.class)) {
      UserLoginToken userLoginToken = method.getAnnotation(UserLoginToken.class);
      if (userLoginToken.required()) {
        // 执行认证
        if (token == null) {
          throw new RuntimeException("无token，请重新登录");
        }
        // 获取 token 中的 user id
        String userId;
        try {
          userId = JWT.decode(token).getAudience().get(0);
        } catch (JWTDecodeException j) {
          j.printStackTrace();
          throw new RuntimeException(j.getMessage());
        }
        User user = userService.findUserById(Integer.parseInt(userId));
        if (user == null) {
          throw new RuntimeException("用户不存在，请重新登录");
        }
        // 验证 token
        JWTVerifier jwtVerifier = JWT.require(Algorithm.HMAC256(user.getUserPwd())).build();
        try {
          jwtVerifier.verify(token);
        } catch (JWTVerificationException e) {
          e.printStackTrace();
          throw new RuntimeException("token已失效");
        }
        return true;
      }
    }
    return true;
  }

}
